GPT on Question 14, Sep 17

I'm writing a bash script to purge orphaned children after the parent dies. What's the idiomatic way?

Bash can reliably clean up children on normal exit or catchable signals by trapping and tracking PIDs:

#!/usr/bin/env bash
set -Eeuo pipefail

children=()

cleanup() {
    local status=$?
    trap - EXIT INT TERM HUP

    if ((${#children[@]})); then
        kill -TERM "${children[@]}" 2>/dev/null || true
        wait "${children[@]}" 2>/dev/null || true
    fi

    exit "$status"
}

trap cleanup EXIT INT TERM HUP

worker1 & children+=("$!")
worker2 & children+=("$!")

wait

This does not run if the parent receives SIGKILL, crashes, or the machine loses power. There is no fully reliable portable Bash mechanism for that.

If descendants can spawn their own children, use OS-level supervision rather than recursively searching by PPID:

•systemd: put the script in a service/cgroup and use KillMode=control-group.
•Linux child wrapper: set prctl(PR_SET_PDEATHSIG, SIGTERM) before exec (not directly available in Bash).
•Dedicated process group/session: possible with setsid, but avoid blindly using kill 0 or kill -- -$$ unless you know the script owns that process group, since it may kill unrelated processes or itself prematurely.

For ordinary scripts, the PID-array plus trap pattern is idiomatic; for guaranteed cleanup after abrupt parent death, use a supervisor/cgroup.

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Sep 17, the whole day Question 14, every day

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Bash can reliably clean up children on normal exit or catchable signals by trapping and tracking PIDs:
```bash
#!/usr/bin/env bash
set -Eeuo pipefail
children=()
cleanup() {
    local status=$?
    trap - EXIT INT TERM HUP
    if ((${#children[@]})); then
        kill -TERM "${children[@]}" 2>/dev/null || true
        wait "${children[@]}" 2>/dev/null || true
    fi
    exit "$status"
}
trap cleanup EXIT INT TERM HUP
worker1 & children+=("$!")
worker2 & children+=("$!")
wait
```
This does **not** run if the parent receives `SIGKILL`, crashes, or the machine loses power. There is no fully reliable portable Bash mechanism for that.
If descendants can spawn their own children, use OS-level supervision rather than recursively searching by PPID:
- **systemd:** put the script in a service/cgroup and use `KillMode=control-group`.
- **Linux child wrapper:** set `prctl(PR_SET_PDEATHSIG, SIGTERM)` before `exec` (not directly available in Bash).
- **Dedicated process group/session:** possible with `setsid`, but avoid blindly using `kill 0` or `kill -- -$$` unless you know the script owns that process group, since it may kill unrelated processes or itself prematurely.
For ordinary scripts, the PID-array plus `trap` pattern is idiomatic; for guaranteed cleanup after abrupt parent death, use a supervisor/cgroup.

End of response · 37 lines · 1,331 characters · sha256 09fda7b6e8d0802d3408c89c2e40988f38c3fe4502c9db24ac583998149d5bf7